Power lift system

ABSTRACT

A power lift system is disclosed for use in association with scaffolding type systems. The system is designed to be erected in close proximity to a building wall or other support structure and is used to lift substantial loads to a desired elevation. The lift system has particular application for use in association with construction and/or the repair of a structure where a crane or elevator is not suitable or available. The power lift system comprises at least one vertical lift combination that comprises an upright member and an associated carrier, the upright member has a rack portion on an exterior surface thereof that extends in the length of the upright member, the carrier is mounted on and moveable in the length of the upright member with the carrier sleeving the upright member, an open slot is provided in the carrier opposite the rack portion and this slot extends the length of the carrier, the vertical lift combination includes a self breaking motor drive and gear train mounted on the carrier and including a drive port in the carrier on a surface of the carrier opposite the open slot with a gear of a gear train extending through the port and engaging the rack portion, the carrier above and below the motor drive includes the means for releasably receiving load arms and these load arms are designed to support a work surface outwardly of the carrier. The power lift system preferably includes at least two vertical lift combinations spaced apart from one another and maintained in a parallel manner. A common work deck can be supported between the two vertical lift combinations.

FIELD OF THE INVENTION

The present invention relates to power lift systems and in particular relates to a power lift system for lifting heavy materials for example masonry or stone products. The system can be erected and dismantled in a straightforward and time efficient manner.

BACKGROUND OF THE INVENTION

There are a number of power lift systems that have been proposed for use in association with scaffolding type systems. These systems are designed to be self standing or erected in close proximity to a building wall and temporarily connected thereto for additional stability. Such power lift systems are designed to assist workmen with respect to the construction and/or repair of a structure where a crane or elevator is not suitable or available.

Power lift systems that operate on the basis of a stabilized vertical upright with a moveable platform that slides on the vertical upright are known. Examples of such systems are shown in U.S. Pat. No. 6,883,643, U.S. Pat. No. 5,884,725 and U.S. Pat. No. 4,382,488.

U.S. Pat. No. 4,382,488 discloses a pump jack pole system having a hydraulic pump jack used to move a slide member up and down a pole upright.

Vertical lift systems that are effectively powered by the workmen are desirable in that the cost of a manual pump jack or a manual crank for lifting of a platform is inexpensive, however there is a problem with respect to providing a safe and cost-effective system that is easy and convenient to use. The purpose of such a lift system includes lifting often heavy material to a higher level. As the weight of this product substantially increases the convenience of a manually driven system is severely compromised.

The present invention is directed to a lifting system that is suitable for lifting of a substantial weight for example in excess of 2,000 lbs. but is also useful in lifting lighter loads and providing an adjustable height work platform.

The system is based on an upright member having a rack portion of one side that cooperates with a gear drive carried and the carrier that slides up and down the upright member. An electric motor is used to drive the gear drive and determine the position of the carrier on the upright. The vertical upright can be used in pairs for larger platforms and work surfaces however it is also possible to use a single upright system.

SUMMARY OF THE INVENTION

A power lift system according to the present invention comprises at least one vertical lift combination with each vertical lift combination comprising an upright member and an associated carrier. The upright member has a rack portion on an exterior surface thereof with the rack portion extending in a length of the upright member. The carrier is mounted on and moveable in the length of the upright member with the carrier sleeving the upright member. The carrier includes an open slot on a surface thereof opposite the rack portion with the open slot extending in the length of the carrier. The vertical lift combination includes a self braking motor drive and gear train mounted on the carrier. The carrier includes a drive port on a surface of the carrier opposite the open slot with a gear of the gear train extending through the drive port and engaging the rack portion. The carrier above and below the motor drive includes means for releasably receiving load arms with the load arms supporting a work surface outwardly of the carrier.

In an aspect of the invention, the power lift system includes at least two vertical lift combinations spaced apart from each other and maintained in a parallel manner.

In a further aspect of the invention, the system has two power lift combinations and the carriers jointly secure a work platform between the upright members.

In yet a further aspect of the invention, each upright member includes a series of securement ports aligned with the open slot of the associated carrier.

In a different aspect of the invention, the system includes a tie off member to releasably engagable with any of the securement ports to form a mechanical connection with the upright member. The tie off member is elongate and extends through the open slot of the carrier as the carrier moves past the tie off member.

In a related aspect of the invention, the tie off member is a rigid member and includes means for fixedly securing the rigid member to a building structure to maintain the upright in a vertical orientation.

In a preferred aspect of the invention, the system includes guide wire securing members engagable with the uprights adjacent an upper edge of the uprights.

According to an aspect of the invention, the system includes two uprights with two carriers and the drive motors of the carrier are commonly controlled to operate in a synchronized manner.

In yet a further aspect of the invention the means for releasably receiving load arms includes two pairs of carrier bars on opposite sides of the carrier. Each pair of carrier bars is rigidly secured to the carrier and generally perpendicular to a length of the carrier. The pairs of carrier bars define parallel securing slots on opposite sides of the carrier sized to slidably receive a securing fork of the load arms. The system includes means for releasably maintaining the securing fork between the pairs of carrier bars.

In a preferred aspect of the invention, the load arms extends forwardly and rearwardly of the carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are shown in the drawings wherein:

FIG. 1 is a perspective view of the system using a single upright member;

FIG. 2 is a perspective view of the system using two vertical members;

FIG. 3 is a partial perspective view of a single pole lifting system showing additional details of the slideable carrier;

FIG. 4 a is a partial exploded perspective view of the slideable carrier, the drive thereof and the cooperation with the vertical upright member;

FIG. 4 b is a sectional view through the vertical pole member;

FIG. 5 is a sectional view showing the slideable carrier, the motor drive thereof and the gears associated with the motor and the rack provided on the upright member;

FIG. 6 is a partial perspective view showing the securement of a work platform to one side of the carrier;

FIG. 7 is a partial perspective view showing an extension member used for lifting of a further upright member to a first upright member;

FIG. 8 is a side view showing the extension member secured on one upright member and the process for lifting and securing a second upright member; and

FIGS. 9 and 10 are perspective view of an alternate embodiment of the slidable carrier.

DETAILED DESCRIPTION

The power lift system 2 shown in FIG. 1 is in an erected position adjacent the house 1. The power lift system 2 includes one or more vertical uprights 4, a powered lift platform 6, side stabilizing cables 8 and vertical standoffs 10. The vertical upright 4 can be stacked one on top of the other by means of a connector extension 12. In the example shown in FIG. 1, there is a base vertical upright 10 a connected to a second vertical upright 10 b. The intermediate connector 12 extends the vertical uprights and also includes spigot portions that are received within each of the vertical uprights to add stability.

In an alternate arrangement a connecting spigot is provided at an upper end of the vertical upright. This spigot receives a base of an upright whereby a separate intermediate connector is not required. Preferably the connecting spigot is welded to partially extend from the vertical upright.

In FIG. 1, a one tier work platform 18 a is shown that is attached to and moves with the slidable carrier 20. This platform 18 can be used as a working surface for the workmen and/or to lift material to a desired height.

In FIG. 2, the power lift system 2 is shown with two vertical uprights 4 generally positioned at opposite sides of the work platform 18 b. The work platform includes hinged or removable sections 19 to allow the work platform 18 b to slide onto the carrier. In the example of FIG. 2, two rigid vertical standoffs 10 are shown in combination with a rigid cross brace member 14 provided between the uprights.

The partial perspective view of FIG. 3 shows additional details of a single vertical upright in this case supporting a two tier work platform 18 c. Also visible in this figure is the intermediate connector 12 joining a base upright 4 a and a first raised upright 4 b. The two-tier work platform 18 c includes the first work surface 21 (suitable as a walk surface for workmen) and a raised or table work surface 23.

Details of the cooperation between an upright 4 and the slidable carrier 20 are shown in FIG. 4 a. The vertical upright 4 includes on a rear surface thereof the rack 30 for cooperation and engagement with gear 28 associated with the drive gear 26 powered by the motor 27. The gear 28 extends through the port 29 provided in the slidable carrier 20. The front face of the slidable carrier 20 includes an open slot portion 22 that allows the carrier 20 to slide past various structural members that are used to connect the pole and stabilize the pole such as the vertical standoffs 10. In this way the slidable carrier 20 can pass upwardly along the connected uprights and move past any vertical standoffs 10. The hinged sections 19 of the work platform 18 can be opened to allow the platform to move past the standoffs 10.

The slidable carrier 20 includes upper carrier bars 40 on opposite sides of the slide carrier and these will receive and engage structural members associated with the work platform or lifting arms. The carrier bars 40 are provided in pairs with a first pair of carrier bars on one side of the carrier and a second pair of carrier bars are provided on an opposite side of the carrier. The retaining plates 42 engage of these structural members and retain the structural members at the sides of the slidable carrier (see FIG. 6). A lower set of carrier bars 50 are provided near the base of the slidable carrier 20 and include retaining plates 52. Bearings 62 are provided on the rear face of the slidable carrier 20 and a similar set of bearings 64 are provided on the front face 51 of the slidable carrier 20. These bearings are located top and bottom of the slidable carrier and oppose binding of the slide carrier with the upright member.

In an alternate embodiment the slidable carrier 20 is extended and side bearings are provided above the upper carrier bars 40 on each side of the carrier and below the lower carrier bars 50 on each side of the carrier. These additional bearings counter any side loads that may occur for example due to non equally distributed loads being lifted. Also this alternate embodiment is more robust and durable (see FIGS. 9 and 10).

The motor 27 is an electric reversible motor that includes its own brake system. There are various manufacturers of these motors but the motor locks when not operating and therefore the carrier is maintained in a fixed location unless the motor is operating. One example of a suitable electric motor is sold by Nord Gear as UNICASE™, Helical worm gear box 3 hp SK32100-100LH. This provides a positive brake mechanism for the slidable carrier 20.

Returning to FIG. 4 a, in addition to the pairs of upper and lower carrier bars 40 and 50, the slidable carrier 20 includes a series of reinforcing wraps 60 that are welded to the slidable carrier. These reinforcing wraps oppose any tendency of the carrier to open or spread and thereby increase the size of the open slot 22. These wraps provide positive reinforcement that avoids any force tending to open the slidable carrier. The reinforcing wraps are typically welded to the slidable carrier 20. Similarly, the rack 30 is a separate member as shown in FIG. 4 b that has been secured within the vertical upright 4. It is desirable to cut a slot in the vertical member and weld the separate rack member 30 into the slot. This two part assembly simplifies manufacture of the rack and the upright.

Various ports are provided at the side of the upright members as well as on the front face for securement of structural members or accessories.

FIG. 6 shows securement of the walker arm 70 to the slidable carrier 20. The walker arm 70 includes opposed members 72 and 74 that are spaced to closely engage the slidable carrier 20 and to be positioned between the upper or lower carrier bars and secured therebetween. A series of tabs 76 include threaded ports for effectively securing of the work platform 78 to the walker arms. The large open ‘U’ shaped opening 80 provided between the two members 72 and 74, allow the walker arm to extend to the front and to the rear of the slidable carrier 20. One portion of the arms will receive the rear part of the work surface 78 and the forwardly extending portion of the walker arms, defined by members 72 and 74, will receive the work surface 80. Note, that work surface 80 includes a slidable portion that allows it to be positioned either side of the slidable carrier 20 and allows movement past standoff members 10.

FIGS. 7 and 8 show one particular embodiment where the extension member 100 includes securing arms 102, 104, having securing hooks 106 and 108. These securing hooks 106 and 108 can be placed within the ports 110, provided in the side of the vertical uprights 4. Two sets of hooks are provided to opposite sides of member 100 to allow it to be positioned to either side of the vertical upright member. A large pulley 112 is provided at one end of the extension member and a rope and hook arrangement passes therethrough and allows a second vertical member to be drawn up and placed on top of a lower vertical member; this aspect is generally shown in FIG. 8. This provides a simple mechanism for initially erecting the desired vertical members one on top of the other and using appropriate standoff members and stabilizing cables for securing of the structure. This extension member 100 is also helpful in taking the system down. An intermediate connector has not been shown but would be present to provide the connection between the upright members or the upright would include an integral spigot.

FIGS. 9 and 10 are perspective views of an alternate slidable carrier 120 having a modified arrangement for mounting of the electric motor drive 124 as well as including side bearings 132, 134, 136 and 138 provided in pairs to opposite sides of the slidable carrier. The alternate slidable carrier is in contrast to the slidable carrier 20 of the earlier figures that included slide plates provided on the sides of the carrier. A slidable carrier with slide plates can be used where low side loads are exerted on the slidable carrier the additional bearings 132, 134, 136 and 138 are preferred particular for applications where side loads are higher.

The electric motor drive 124 has a two-way electrical motor 150 in combination with a transmission drive 152 that drives the drive gear 154 that is in mesh with the rack 30 of the vertical upright. The electric motor 150 and transmission 152 are mounted on a mounting plate 160 that extends to one side of the slidable carrier 120 and is secured preferably by welding to the slidable carrier on two sides thereof. This provides a strong “L” shaped mounting plate for the electric motor 150 and transmission 152 that overlaps with the slidable carrier. As can be appreciated due to the extra bearings provided on the alternate slidable carrier the length of the carrier has increased.

With the arrangement as shown in FIGS. 9 and 10, the electric motor and transmission are provided to one side of the carrier and generally are in close proximity and extend in the length of the slidable carrier. This provides a compact and space efficient design that is rugged and less subject to damage.

As can be appreciated, the power lift system of the present invention provides a simple arrangement for raising of various loads to different elevations and can quickly be erected and dismantled as required. The components are relatively rugged and cost effective to manufacture. The slidable carrier 20 is adapted to allow for a single level work surface or a multi-level work surface as may required for different jobsite applications. For example, some projects may have a users walk platform using the lower carrier bars 50 and a raised or table type platform using the upper bars 50 and provided to the rear of the carrier.

The system also allows easy conversion from a one post system to a two post system or more. This provides versatility as may be required from job to job for lifting of different weights and/or applications.

The system is particularly designed for lifting of weights in excess of 2000 lbs. that may be required for certain jobs, particularly masonry or replacement window applications.

Although preferred embodiments of the invention, which are described here in detail, may be understood by those skilled in the art; there are variations we have made thereto without departing from the spirit of the invention, or the scope of the appended claims. 

1. A power lift system comprising at least one vertical lift combination with each vertical lift combination comprising an upright member and an associated carrier; said upright member having a rack portion on an exterior surface thereof and extending in a length of said upright member; said carrier being mounted on and moveable in the length of said upright member with said carrier sleeving said upright member; said carrier including an open slot on a surface thereof opposite said rack portion and extending the length of said carrier; said vertical lift combination including a self braking motor drive and gear train mounted on said carrier, said carrier including a drive port on a surface of said carrier opposite said open slot with a gear of said gear train extending through said drive port and engaging said rack portion; said carrier above and below said motor drive including means for releasably receiving load arms, said load arms supporting a work surface outwardly of said carrier.
 2. A power lift system as claimed in claim 1 comprising at least two vertical lift combinations spaced and maintained in a parallel manner.
 3. A power lift system as claimed in claim 2 wherein said system has two power lift combinations and said carriers jointly secure a work platform between said upright members.
 4. A power lift system as claimed in claim 3 wherein each upright member includes a series of securement ports aligned with said open slot of the associated carrier.
 5. A power lift system as claimed in claim 4 including a tie off member designed to releasably engage any of said securement ports and form a mechanical connection with said upright member, said tie off member being elongate and extending through said open slot of said carrier as said carrier moves past the tie off member.
 6. A power lift system as claimed in claim 5 wherein said tie off member is a rigid member including means for fixedly securing thereof to a building structure to maintain said upright in a vertical orientation.
 7. A power lift system as claimed in claim 6 including guide wire securing members engagable with said uprights adjacent an upper edge of said uprights.
 8. A system as claimed in claim 7 including at least one guide wire securing each upright member and extending downwardly and outwardly from said upper edge of the upright member.
 9. A system as claimed in claim 8 including a rigid structural brace secured between said upright members at said upper edges.
 10. A system as claimed in claim 8 wherein said drive motors are commonly controlled to operate in a synchronized manner.
 11. A system as claimed in claim 3 wherein said means for releasably receiving load arms includes two pairs of carrier bars on opposite sides of said carrier, each pair of carrier bars being rigidly secured to said carrier and generally perpendicular to a length of said carrier, said pairs of carrier bars defining parallel securing slots on opposite sides of said carrier sized to slidably receive a securing fork of said load arms and means for releasably maintaining said securing fork between said pairs of carrier bars.
 12. A system as claimed in claim 11 wherein said load arms extending forwardly and rearwardly of said carrier. 